1. Lecture 19 Placentation and Maternal Recognition of Pregnancy
Animal Science 434
John J. Parrish

2. Blastulation Gap Junctions Inner Cell Mass Zona Pellucida
Trophectoderm
Na+
[Na+]
H2O
Tight Junctions

3. Hatching
Bovine
days
Equine, Ovine
7 - 8 days
Porcine
6 days

4. Mare remains spherical!
Conceptus Growth
Cow
Day 15, 1-2 mm
Day 18-19, cm
Occurs in cow, pig and sheep
Spherical
Embryonic Area
Tubular
Elongating
Trophoblast
Mare remains spherical!
Filamentous

5. Development of Porcine Conceptuses from Day 10 to 12
5 mm Spherical
10 mm Spherical
Inner Cell
Mass
15 mm Tubular
150 mm
Filamentous

6. Elongated Day 15 Porcine Conceptus
Embryo

7. Uterine Location of Elongating Ruminant Blastocyst
Corpus
Luteum
Bovine and Ovine

8. Pig Intrauterine Migration
Day 5

9. Pig Intrauterine Migration
Day 7

10. Pig Intrauterine Migration
Day 12
Embryos become fixed
Transuterine migration is rare in cow and ewe!

11. Trans-uterine Migration in the Mare
Begins Day 10
Fixation can occur in either horn!
Fixation on day
Corpus
Luteum

12. Formation of Germ Layers
Gastrulation
Trophectoderm
Inner Cell Mass
Formation of Germ Layers
Endoderm
Blastocoele
Cavity

13. Gastrulation
Endoderm
Endoderm
Yolk Sack

14. Gastrulation
Endoderm
Endoderm
Yolk Sack

15. Gastrula
Ectoderm
Trophectoderm
Endoderm

16. Trophectoderm (Chorion)
Gastrula
Ectoderm
Mesoderm
Extraembryonic
Coelom
Yolk Sack
Endoderm
Trophectoderm (Chorion)

17. Germ Layers Ectoderm Mesoderm Endoderm CNS Sense organs Mammary glands
Sweat glands
Skin
Hair
hooves
Mesoderm
Circulatory
Skeletal
Muscle
Reproductive tracts
Kidneys
Urinary ducts
Endoderm
Digestive
Liver
Lungs
Pancreas
Thyroid gland
Other glands

18. Extraembryonic Ceolom
Placenta Formation
Embryonic
Ectoderm
Amniotic Folds
Extraembryonic Ceolom
Yolk Sack
Trophectoderm
Chorion
Mesoderm
Endoderm

19. Extraembryonic Ceolom
Amniotic Fold
Amniotic Cavity
Allantois
Extraembryonic Ceolom
Yolk Sack
Chorion

20. Extraembryonic Ceolom
Amnionic Cavity
Amnion
Uterine
Lumen
Allantois
Yolk Sack
Chorion
Extraembryonic Ceolom
Carnuncle

21. Amniotic Cavity
Chorion
Amnion
Allantois Cavity
Yolk
Sack
Allantochorion
(Chorioallantois)
Cotyledon

22. Placental Membranes Yolk Sack Amnion In birds to nourish embryo
In mammal atrophies but source of blood cells and primordial germ cells
Amnion
Non-vascular, fluid filled
Fluid produced by fetus
Protective cushion
Ruptures at birth (not breaking of water)

23. Placental Membranes (cont.)
Allantois
Blood vessels
Fuses with chorion
Allantochorion or chorioallantois
Brings blood vessels to chorion
Chorion
Outermost membrane
Attachment to mother

24. Maternal Recognition of Pregnancy

25. Luteal Regression PGF2a (Bovine, Ovine, Porcine) PGF2a (Equine)
No Uterine Factor
(human)

26. CL Status CA Mechanisms CL Regression Luteolytic No CL support
CL Maintenance
Antiluteolytic
Block PGF2a effects
Luteotrophic
Stimulate progesterone production by CL
(+)
Uterine PGF2a CL
Filamentous Embryo
(+)
Maintained

27. Recognition of Pregnancy
Conceptus Secretions
Proteins
Steroids

28. Recognition of Pregnancy in Bovine and Ovine
Conceptus Secretions
Interferons
oIFN-t
bIFN-t
Mechanism
Antiluteolytic
Inhibit oxytocin receptor synthesis
Inhibit PGF2a synthesis
Critical Days
Bovine - 16 to 17
Ovine - 12 to 13

29. Recognition of Pregnancy in the Porcine
PGF2a

30. Recognition of Pregnancy in the Porcine
PGF2a
PGF2a
PGF2a

31. Recognition of Pregnancy in the Porcine
Conceptus Secretions
Estradiol
PGF2a E2
Critical Days
11 to 12
Mechanism
Antiluteolytic
Redirect PGF2a
Requires 2 embryos per horn

32. Recognition of Pregnancy in the Mare
PGF2a
Mechanism
antiluteolytic
Conceptus Secretion ?
Critical Days
10 to 14

33. Recognition of Pregnancy in the Human
Conceptus Secretes
HCG
Mechanism
luteotrophic
HCG
Critical Days
8 to 12

34. Recognition of Pregnancy
INF-t
HCG
Estradiol
Conceptus Secretions
Proteins
Steroids

35. Dog and Cat CL does not regress if not pregnant Psuedopregnancy
no uterine effect
Psuedopregnancy
CL last similar length as in pregnancy

36. Implantation

37. Time of Implantation Attachment to Uterus Species Beginning Completion
pig 13 24
cow 22 40
sheep 15 28
mare
human

38. Type of Implantation Superficial Eccentric Interstitial
Chorion lies opposed to uterine wall
Farm animals
Eccentric
Chorionic sack in a uterine fold
Rodent
Interstitial
Embryo digests part of uterine wall
human

39. Degree of Tissue Loss at Parturition
Deciduate
Eccentric, interstitial
Rodent, human
Indeciduate or Nondeciduate
Superficial
Farm animals

40. Shape or Distribution of Chorionic Villi
Cotelydonary - cow, sheep
Diffuse - pig, horse
Zonary - dog, cat
Discoid - human

41. Cotelydonary Placenta
Cow
Convex
Ewe
Concave
Cotelydon (Chorion)
Caruncle
Endometrium

42. Cotelydonary Placenta
Cow
Ewe
Placentome

43. Placental Attachment in Ruminant
Binucleate
Cell
Chorion
Migrate and
fuse with
uterine
epithelium
Uterine
Epithelium
Syncytium
Capillary
Fusion of
Binucleate
cells and
uterine
epithelium
(multinucleate)
Stroma

44. Day 23 Migration of Bicnucleate Cells and Formation of Syncytium
Binucleate
Cell
Endometrial
Stroma
Multinucleated Cells in
Uterine Epithelium

45. Binuclear Giant Cells 20% of fetal placenta Invade endometrium Source
Placental lactogen
Pregnancy specific protein B

46. Placental Lactogens (Protein Hormones)
Prolactin-like activity:
Stimulates Milk Synthesis
Not Present in Pig and Mare
May regulate maternal metabolism to facilitate fetal growth
High levels in the last 1/3 of gestation.
High levels facilitate higher milk production.
Dairy cows have higher blood concentrations than beef cows

47. Pregnancy Specific Protein B
Unique to ruminants
Function uncertain
Has been used to detect pregnancy
Cattle, sheep, deer
Can be used to detect pregnancy in cows after day 25
Not early pregnancy factor!!!

48. Diffuse Placenta
Horse
Pig
Microcotyledons

49. Increase placental surface area Microcotelydon (Fetal)
Microcotelydons
Increase placental surface area
Microcotelydon (Fetal)
Microcotelydon
Epithelium
Microcotelydon
(Maternal)
Endometrial Glands
Endometrium
Uterine Arteries
Uterine Veins

50. Endometrial Cups in Mare
From both trophoblast and endometrium
5 to 10
Form between days 35 to 60
Produce equine chorionic gonadotropin (eCG, PMSG)
Sloughed off after day 60

51. Zonary Placenta (bitch, queen)

52. Discoid Placenta (human)

53. Cell Layers Separating Maternal and Fetal Blood
Capillary
Capillary
Endothelium
Endothelium
Connective
Tissue
Connective
Tissue
Chorionic
Epithelium
Endometrial
Epithelium

54. Histological Classification
Tissues epithelial- syndesmo- endothelial- hemo- hemo-
chorial chorial chorial chorial endothelial
Maternal
endothelium
conn. tissue
epithelium
Fetal
epithelium
conn. tissue
endothelium
Species pig *ruminant dog human rat
horse cat rabbit
ruminant

55. Important!!!!
In all cases, fetal and maternal blood does not mix.